Large magnetoelectric coupling in multiferroic oxide heterostructures assembled via epitaxial lift-off

Abstract

Epitaxial films may be released from growth substrates and transferred to structurally and chemically incompatible substrates, but epitaxial films of transition metal perovskite oxides have not been transferred to electroactive substrates for voltage control of their myriad functional properties. Here we demonstrate good strain transmission at the incoherent interface between a strain-released film of epitaxially grown ferromagnetic La_0.7Sr_0.3MnO₃ and an electroactive substrate of ferroelectric 0.68Pb(Mg_1/3Nb_2/3)O₃-0.32PbTiO₃ in a different crystallographic orientation. Our strain-mediated magnetoelectric coupling compares well with respect to epitaxial heterostructures, where the epitaxy responsible for strong coupling can degrade film magnetization via strain and dislocations. Moreover, the electrical switching of magnetic anisotropy is repeatable and non-volatile. High-resolution magnetic vector maps reveal that micromagnetic behaviour is governed by electrically controlled strain and cracks in the film. Our demonstration should inspire others to control the physical/chemical properties in strain-released epitaxial oxide films by using electroactive substrates to impart strain via non-epitaxial interfaces.

Key properties of transition metal perovskite oxides are degraded after epitaxial growth on ferroelectric substrates due to lattice-mismatch strain. Here, the authors use epitaxial lift-off and transfer to overcome this problem and demonstrate electric field control of a bulk-like magnetization.